Swine dysentery is a severe mucohaemorragic diarrhea primarily affecting pigs post weaning. Control of the disease has been generally accomplished through use of chemobiotics and antibiotics. To date, there has been no effective nondrug prophylactic agent to control this disease. The anaerobic spirochete, Treponema hyodysenteriae, is recognized to be the primary etiological agent of swing dysentery. U.S. Pat. No. 4,100,272 discloses the use of a vaccine or bacterin containing killed cells of T.hyodysenteriae to increase the resistance of swine to swine dysentery.
This prior art method has not resulted in commercial acceptance, because the bacterin product has relatively low activity. The described treatment schedule includes six intravenous injections. It is desired to have a bacterin that can be used in a treatment schedule involving fewer intramuscular injections.
Cholesterol-rich fractions are known to be useful as growth promoters for some organisms. J.Bacteriol., Vol. 135, No. 3, pp. 818-827 (1978) describes the use of a cholesterol-rich fraction as a growth promoter for Mycoplasma pneumoniae and Mycoplasma arthritidis. J.Gen.Microbiology, Vol. 116, pp. 539-543 (1980) describes the use of USP cholesterol in the growth of T.hyodysenteriae.
There is no known prior art that suggests the specific use of cholesterol-rich bovine fractions to enhance the yield of cells of T.hyodysenteriae for subsequent inclusion in a bacterin suitable for control of swine dysentery.